鋳鋼ブレーキディスク材のすべり摩擦試験で得られる白色層組織

抄録

  It is known that the white layers formed on cast steel brake disks for railway that have high hardenability during braking tests become lath martensite, which is a fully quenched microstructure. In this study, such white layers were reproduced on cast steel by sliding friction test, and their microstructure was investigated. Severe friction was applied on the specimens using a WC-Co bar with high pressure which raised the temperature of the specimens to above the material's Ac3 point. These white layers were observed on the friction surface of the specimens after the friction test, and the results of investigations of the microstructure by SEM and TEM identified the white layers to be a sub-micron equal axial microstructure with 30 to 100nm grain. The white layers were different from those formed on brake disks, which are known to be lath-martensite with coarse grain.